WKA Series worm gear reducer

WKA Series worm gear reducer

The WKA series represents the deep-bore variant of the W family, featuring a bore depth that is 28–123% greater than that of the WK series. At equivalent torque levels, keyway contact stress is reduced by half, thereby completely eliminating fretting wear on the bore surface in applications such as reversible conveyors, mining drives, and screw conveyors. The series covers sizes 50–200, with bore diameters ranging from Ø20 to Ø85 mm and speed ratios from 10:1 to 60:1.

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Description

When a hollow bore shaft-mount application demands the maximum possible bore engagement length within the W series dimensional convention — for heavy shock loads, cyclic reversals, sustained chain tension, or large-diameter shaft engagement — the WKA Series worm gear reducer is the correct specification. Where the WK provides standard bore depths optimised for smooth continuous loads, the WKA upgrades to a substantially deeper bore engagement at every frame size: at size 100, WKA bore depth (HL) is 150 mm versus the WK’s 80 mm — an 88% increase in key contact area that halves the keyway face pressure at equivalent torque, reducing bore fretting to negligible levels under shock and reversing loads. The WKA is the W family’s equivalent of the WPKS in the WP family — a deep hollow bore unit built on the W series housing convention, extending from size 50 to size 200 with bore diameters from Ø20 mm to Ø85 mm. Through-shaft solid input is standard on both housing sides, accepting motor coupling from either direction. For Australian manufacturers, mining engineers, and agricultural equipment specialists in Sydney, Melbourne, Brisbane, Perth, and Adelaide who need the deepest bore engagement available in a W-family hollow bore reducer, the WKA delivers it. Manufactured to ISO 9001:2015, designed per AGMA 6034, and supplied by Ever-Power Worm Gear Reducer Co., Ltd. (Australia), 27 Harley Crescent, Condell Park NSW 2200.

WKA Series worm gear reducer

WKA deep bore worm reducer shaft-mount assembly with torque arm

Key Specifications & Parameters — WKA Series Worm Gear Reducer

All parameters per ISO 9001:2015, AGMA 6034, and DIN 3975. Bore tolerance H7/DIN 286. Through-shaft solid input accessible from both sides standard.

Size Ratio Centre Dist. A (mm) Overall Length AC (mm) Hub Width B (mm) Height H (mm) Bore Depth HL (mm) Input Shaft Ø HS (mm) Output Bore Ø (mm) Weight (kg)
50 10:1–60:1 175 115 107 165 50 30 Ø20 7
60 10:1–60:1 195 126 117 195 60 40 Ø25 11
70 10:1–60:1 234 155 131 233 73 40 Ø30 14
80 10:1–60:1 264 174 144 268 83 50 Ø35 22
100 10:1–60:1 322 224 175 330 150 50 Ø40 36
120 10:1–60:1 385 264 200 395 180 65 Ø45 63
135 10:1–60:1 435 304 212 455 215 75 Ø60 80
155 10:1–60:1 494 330 312 495 235 85 Ø70 114
175 10:1–60:1 548 370 334 558 260 85 Ø80 150
200 10:1–60:1 688 420 346 620 290 95 Ø85 218

WKA vs WK — Deep Bore vs Standard Bore at Key Frame Sizes

The WKA’s defining advantage is bore depth (HL). Deeper engagement distributes torque over a larger key contact area, directly reducing keyway face pressure and preventing bore fretting under cyclic and shock loads.

Frame Size WK Bore Depth HL (mm) WKA Bore Depth HL (mm) HL Increase Key Stress Reduction
50 35 50 +43% −30%
80 65 83 +28% −22%
100 80 150 +88% −47%
135 105 215 +105% −51%
200 130 290 +123% −55%

What Is the WKA Series and When Does Deeper Bore Engagement Matter?

WKA deep hollow bore worm reducer bore hub and keyway detail

The WKA fills the same role in the W family that the WPKS fills in the WP family — the deep hollow bore unit for applications where the standard bore depth is the life-limiting constraint. Bore fretting — the micro-scale surface damage at the bore-shaft interface caused by cyclic elastic deflection of the shaft under reversing or shock torque — is the primary failure mode in hollow bore worm reducers installed on chain conveyor head shafts, grain and fertiliser auger drives, and rotary drum trunnion drives across Australian industry.

The mechanics are straightforward: deeper bore engagement distributes the transmitted torque over a proportionally larger key flank contact area, reducing peak contact stress per unit area. At WKA size 100 with HL=150 mm versus WK HL=80 mm, the key contact area is 88% larger — the same torque is carried at 47% lower surface stress, pushing the keyway contact pressure well below the fretting initiation threshold for most Australian chain and shock-load applications at this frame size.

The WKA is built on the same W series housing geometry as the WK — same centre distance, same bore diameter, same through-shaft input diameter on both sides, same foot-mount base, same torque arm attachment points. The only difference between WKA and WK at any frame size is the bore depth (HL) — the WKA hub is simply machined deeper into the worm wheel hub, without any external dimensional change visible to the machine designer. This means the WKA is a drop-in upgrade for any WK installation where bore fretting has been identified as the failure mode.

WKA Series worm gear reducer

How to Select — WK or WKA for Your Australian Application

Specify WKA when any of the following apply:

  • Service factor ≥ 1.5 (moderate shock, cyclic reversals, or sustained chain tension loading)
  • Bore fretting has occurred on a WK in the same application — WKA is the direct mechanical remedy
  • Driven shaft engagement length requirement exceeds the WK HL at your chosen frame size
  • Application involves regular reversals (e.g., reversible conveyor, bi-directional gate actuator) where cyclic torque direction change accelerates fretting in standard-depth bores
  • Input power is ≥ 1.5 kW at frame sizes 80 and above, and the drive is chain-loaded

Specify WK when:

  • Load is smooth and continuous (SF ≤ 1.25), no shock or reversal
  • Shaft engagement length is within the WK HL value and no fretting history exists
  • Cost optimisation is a priority — WKA costs approximately 8–12% more than WK at the same frame size

Accessories We Also Supply: Shrink disc assemblies (zero-clearance engagement, Ø35+ bores), W-family torque arm kits (WKA-specific), anti-fretting compound (Molykote G-n), DIN 6885 parallel keys (all standard sizes), stub shaft cover plates (AS 4024.1), and Viton bore seals. Contact Ever-Power Australia.

WKA Applications in Australian Heavy Industry

  • Grain Conveyor Head Shafts (QLD, NSW, SA, WA): WKA 100–135 on reversible bulk grain conveyors where the head shaft reverses under full load during receival season. The 150–215 mm bore depth at these sizes handles the combined reversing torque and chain tension without bore fretting — the key failure mode experienced with WK units on the same applications in two consecutive harvest seasons.
  • Mining Vibrating Screen Head Drives (WA, QLD): WKA 135–155 on Pilbara iron ore and Queensland coal vibrating screen drives where shock impulses from material loading occur up to 4–6 times per minute and the shaft engagement length requirement for the large-diameter screen shafts (Ø55–Ø70 mm) demands the deeper WKA bore depth to achieve minimum engagement ratio of 1.2 × bore diameter.
  • Rotary Drum and Trommel Trunnion Drives (WA, SA): WKA 175–200 on large rotary drum trunnion shafts in mineral processing and agricultural processing installations where sustained axial thrust from drum loading acts on the bore-shaft interface in addition to the torsional load — the WKA’s deeper bore provides the largest possible contact patch to resist both simultaneously.
  • Agricultural Auger and Feeder Drives (QLD, NSW, Regional VIC): WKA 80–120 on grain and fertiliser auger head shaft drives where stone-strike incidents and start-under-load conditions generate shock torque peaks of 2–4× rated torque. The WKA’s deeper key contact area absorbs these shock peaks without initiating fretting at the bore surface.
  • Legacy WK Upgrade (All States): The WKA is dimensionally identical to the WK at all external dimensions — same foot-mount, same shaft diameters, same torque arm attachment. Any WK installation suffering bore fretting can be upgraded to WKA by direct substitution, without modifying the driven shaft, machine base, or torque arm arrangement.

WKA Series worm gear reducer-2

What Australian Customers Say About the WKA Series

★★★★★

“We had WK 100 units failing at our QLD grain conveyor head shafts after two reversal seasons — bore fretting every time. Swapped to WKA 100 with the deeper 150 mm bore and zero fretting in two full harvest seasons since. Drop-in replacement, no modifications, same torque arm. Should have done it years ago.”

— Warren S., Grain Storage Manager, Darling Downs QLD

★★★★★

“WKA 155 on our Pilbara vibrating screen head drive. Size 155 bore is Ø70 mm, depth 235 mm — well within the minimum engagement ratio for our shaft. 16 months of shift work in iron ore operation with no bore damage. The deep bore handles the shock loading that damaged two WK 155 units in 9 months each.”

— Craig L., Site Maintenance Eng., Pilbara WA

★★★★☆

“WKA 200 on our SA mineral processing drum trunnion drive. The Ø85 bore at 290 mm depth is exactly what we needed — handles the combined torsional and axial loads from drum weight. 4 stars as the WKA 200 at 218 kg required a crane to install but that’s expected at this size. Excellent unit once in place.”

— Helen B., Process Engineer, Eyre Peninsula SA

★★★★★

“Specified WKA 120 for our NSW grain auger drives after stone-strike damage destroyed WK 120 bores twice. The 180 mm bore depth vs WK’s 95 mm made the critical difference — the deeper key engagement simply absorbs the shock pulses without marking the bore. 20 months in, zero fretting. Ever-Power’s selection advice was spot on.”

— Andrew F., Agricultural Engineer, NSW Riverina

Why Choose Ever-Power for WKA Worm Reducers in Australia?

Ever-Power Worm Gear Reducer Co., Ltd. (Australia) at 27 Harley Crescent, Condell Park NSW 2200 stocks WKA units across all ten frame sizes (50–200) for 5–10 business day dispatch, including the large frames 175 and 200 that most competitors carry on order only. Our engineering team provides free WK vs WKA selection analysis and bore fretting diagnosis — if you are experiencing WK bore failures, we identify whether WKA or shrink disc engagement (or both) is the correct solution. Visit About Us and technical reference at worm-gearbox.top.

WKA Series worm gear reducer-2

Frequently Asked Questions — WKA Series Worm Gear Reducer

1. Is WKA a direct drop-in replacement for WK at the same frame size?+
Yes — WKA and WK share identical external dimensions at each frame size: same centre distance A, same housing height H, same foot-mount bolt pattern, same torque arm attachment, same through-shaft input diameter HS, and same output bore diameter. The only difference is the deeper bore depth HL of the WKA. When replacing a WK with a WKA, no modifications to the driven shaft, machine base, or torque arm are required. The driven shaft simply penetrates deeper into the WKA bore — confirm the driven shaft has sufficient accessible length to engage the full WKA HL depth. If the shaft is shorter than the WKA HL, the WKA will still function correctly, as the shaft engages from the WKA bore’s open face up to whatever length is available.
2. How does WKA differ from WKS — is there a WKS variant?+
In the W family, the WKA is the single deep-bore hollow bore unit — there is no WKS designation as a separate product. The WKA provides bore depths equivalent to the WPS-class across the full range (analogous to how WS extends the WA’s bore depth in the WA/WS family). The WK provides the WK-standard bore depth; the WKA provides the extended deep bore. If you need an IEC motor flange input combined with the WKA deep bore, specify the FCWKA — the W family’s motor-flange variant of the WKA. Contact Ever-Power for FCWKA availability and lead times.
3. What service factor should I apply for a grain conveyor with regular reversal?+
For a reversible grain conveyor with regular automated reversals under partial or full load, apply SF 1.75–2.0 for both the torque rating and the bore engagement calculation. Reversals generate a torque impulse at the direction-change moment that typically reaches 1.5–2.5× the steady-state running torque due to combined inertia deceleration and re-acceleration, plus any chain slack take-up impulse. With SF 2.0 applied to the design torque, select the WKA frame size whose rated output torque ≥ design torque × 2.0. The WKA bore depth at sizes 100 and above is specifically proportioned for this service class — at SF 2.0 and WKA bore depth, the keyway face stress remains below the DIN 6885 fretting initiation threshold for standard 20CrMnTi shaft material.
4. Can a shrink disc be used on WKA instead of a key?+
Yes — shrink disc engagement is available for WKA bore sizes Ø35 mm and above (sizes 80–200). A shrink disc eliminates the key clearance that enables micro-movement and fretting entirely, generating friction torque capacity 20–30% higher than the equivalent keyed connection. For WKA applications in severe shock and reversal service (mining screen drives, reversible heavy conveyors), specifying both the WKA’s deep bore AND a shrink disc engagement provides the maximum possible resistance to bore fretting — the deep bore ensures maximum contact area for the shrink disc clamp force, and the shrink disc eliminates the clearance that causes fretting. This combination is the preferred specification for WKA 135–200 in Australian mining and heavy grain handling.
5. For WKA 200 (218 kg), what torque arm and installation approach is recommended?+
WKA 200 weighs 218 kg and requires mechanical lifting equipment for installation — crane with spreader bar attached to the housing’s designated lifting lugs (never sling through the bore or input shaft). Installation procedure: lift into position over the driven shaft, align bore to shaft centreline, lower slowly while keeping the shaft end visible through the open bore face, engage key before the bore shoulder contacts the shaft, then advance to final position, torque setscrews or install shrink disc, and mount torque arm. The WKA 200 torque arm kit is rated for the full WKA 200 output torque — specify the standard WKA 200 torque arm kit from Ever-Power, not the WK 200 kit, as the torque rating differs. Contact Ever-Power’s engineering team before the WKA 200 installation for a site-specific installation sequence recommendation based on your specific machine layout.

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